Organic brown rice syrup appears to be the arsenic-carrying culprit, and is used in a number of products.

You may think you're being extra-healthy when you chose foods labeled "organic," but some of these products contain arsenic, a compound that may increase the risk of cancer, a new study says.

The study points to organic brown rice syrup, an ingredient often used as a healthy alternative to high fructose corn syrup, as a potential source of arsenic in food.

The results show cereals bars, energy shots and even infant formulas made with organic brown rice syrup contain particularly high levels of arsenic, compared with products without this syrup. Some cereal bars have concentrations of arsenic that are 12 times the U.S. Environmental Protection Agency's (EPA) safe drinking water limit of 10 parts per billion (ppb), the researchers said.

There are two main types of arsenic: organic and inorganic. These terms refer to the chemistry of the arsenic compound; they have nothing to do with pesticide use, as when the term "organic" is applied to foods.

The majority of arsenic the researchers found was inorganic, which is generally thought to be more harmful than organic arsenic. Chronic exposure to low levels of inorganic arsenic has been linked to increased risks of bladder, lung and skin cancer, as well as Type 2 diabetes and cardiovascular disease, according to the EPA.

Recent studies have shown that rice can be a major source of arsenic in our diet. The new study highlights the fact that products we don't normally think of as containing rice may still harbor significant levels of arsenic, the researchers said.

It's not yet clear whether the arsenic in rice, rice-based products or other foods is harmful to people. But the levels found in infant formulas are concerning, because of infants' small body size, said study researcher Brian Jackson, of the department of Earth sciences at Dartmouth College in Hanover, NH.

There are currently no rules in the United States governing how much arsenic is allowed in foods, and the guidelines for water are not a fair comparison, because people may consume more water than arsenic-containing foods.

Still, given that some foods may be a significant source of arsenic, "there is an urgent need to regulate arsenic in food," the researchers wrote in their study.

Arsenic in food

Jackson and colleagues measured the amount of arsenic in 17 infant formulas, 29 cereal bars and 3 energy shots purchased from stores in New Hampshire.

Two of the infant formulas contained organic brown rice syrup as their primary ingredient. These products had arsenic levels 20 to 30 times that of the other infant formulas.

Twenty-two of the cereal bars contained at least one rice product (organic brown rice syrup, rice flour, rice grain or rice flakes) listed as one of the first five ingredients. These bars had levels of arsenic that ranged from 23 to 128 parts per billion (ppb). Cereal bars that did not contain rice had much lower arsenic levels, ranging from 8 to 27 ppb.

The energy "shots", or gel-like blocks, contained between 84 and 171 ppb arsenic. All the products had organic brown rice syrup as one of the ingredients. An individual who consumed four of these energy shots would consume more than 10 micrograms of arsenic — an amount equal to drinking 1 liter of water with arsenic concentration at the current EPA limit.

Babies at risk

Of all the study findings, "the data on the infant formulas is most concerning," said Christopher States, a toxicologist at the University of Louisville in Kentucky. The amount of arsenic consumed by an infant could be significant depending on which formula they drank, States said. In addition, the arsenic concentrations in the study were calculated assuming the infant formula powders were prepared for babies to drink with arsenic-free water. Infants who consumed formulas with high arsenic levels that were mixed with arsenic-containing water would be at the greatest risk for potential health effects, States said.

Recent research suggests arsenic exposure early in life may increase the risk for health problems later on. Formula may be a baby's sole food over a critical period of development, and their small size means they may consume more arsenic per kilogram of body weight than an adult eating foods with similar arsenic levels, the researchers said.

It's hard to say what effect arsenic in foods may have on adults, Jackson said. If guidelines are set for acceptable levels of arsenic in food, they may be higher than most of the levels found in this study, around 200 ppb, Jackson said.

"I don't think eating the occasional cereal bar has any real risk to it," Jackson said. For those concerned about arsenic exposure, Jackson recommends making sure meals are not rice-based. For parents, Jackson said to avoid infant formulas that contain rice syrup.

The article is published on Feb. 16 in the journal Environmental Health Perspectives.